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GEORGE M. HOPKINS AND JOHN A. STRAIGHT, or ALBION, NEWNYORK.

Letters Patent No. 106,821, dated August 30, 1870;y enteric-ted. August13, 1870.

LOWWATER AND HIGH-PRESSURE INDICATOR The Schedule referred to in theseLetters' Patent and making part'ofthe same We, GEORGE M. HOPKINS andJOHN A. STRAIGHT, of AlbiOn, in the county of Orleans and State of NewYork, have invented a certain Improvement in Lowwater Indicators an'dPressure-Alarms', of which the following is a specification.

Nature and Objectlof the Invention.

Our invention relates to the combination of a safetyvalveandexpansion-tube, provided with an air-chamber, in such a way that,when there is a deciency of water in vthe boiler, the expansion of the.tube-raises A t h e -valve and admits steam to the whistle, and, whenthere is an over pressure-of steam in theboiler, the valve will riseindependently of the expansion-tube.

The object of this invention is to furnish a reliable means ot' 'givingan alarm when the water becomes low in the boiler, or when the`safety-valve fails to act from any cause.A

Description ofthe Accompanying Drawing.

,Figure 1 is an elevation of the apparatus, with the whistle and'weighted arm of the safety-valve removed..

Figure 2 is a view ot' the safety-vulve, whistle, and connections.

General Description.

Ik is un expansiOn-tnbe,made ot' any suit-able materia B is anair-chamber attached to or connectedwith thetube A.

O is a small safety-valve, of ordinary construction, except that thevalve-stem d is threaded, and is provided with the nut e.

F is a rod attached to the upper end ofthetube A, the lower end Of whichis bent out at a right angle, and'is provided with a hoIe, through whichthe valvestem d passes. The nut e is-above the bent portion of the rodF.

By reference to Iig. 2 it will be seen that the weighted lever G has itst'ulcrnm at H, andbears upon the valve-stem d. The whistle Iis'vconnected with the valvev C in such a way that the steam whichescapes the valve sounds :the alarm Athrough it.

J is an air-cock, which admits of letting the water down from the tubeA. The lower end of the tube A is connected with the boiler'at thelower-try-cock, as in the drawing, r at any other suitable place.

K is a pipe which conducts steam to the valve C.

The operation is as follows:- j

When the water in the boiler is above the point at which the indicatoris attached, the tube A is full of water, and remains cool; but when thewater drops below the point at which the indicator is attached, thewater in thetube A gradually runs back into the boiler, and steamenters, heating and, consequently, expanding it, raising the valve C bymeans of the rod F, when steam passes through thewhistle I, giving analarm, which continues until the water is again -above the point atwhich the indicator is attached,`

when the water again fills the tube A, and, cooling, allows the tube tocontract, when the valve C closes and the alarm ceases. Should the steamat any time rise above" the limit at which the Valve C is Weighted, .itwill rise indepeudently ofthe tube A, and the escaping steam willA givethe alarm through the whistle I.

As previously described, it will be seen that the -stem ot' the doublealarm-valve projects beyond the shell or casing, and is embraced by thelower end ot.

the rod F. The nut e is fitted- Onthe stern, so that the rod is retainedthereon, and thereby bears against the nut when the'tnbe expands, andthus the valve isv opened.

When the tube cools and contracts, the -rod. is lowered, and allows theweight which rests on the stem to close the valve.

We are aware that expansible "tubes, connected by non-expansible tubesor rods to the. alarm-valve, have been in use, for the purpose Otsounding an alarm in the -event'otlow water in the.- boilcr; but, asifaras we are aware; such tubes, when provided with an airchamber, in themanner hereinbefore indicated, have not been used in connection withavalve that-could he raised by the steam pressure within the boiler.

. We are also aware thatit has been proposed to connect an expansibletube with'an alarm-valve, in such away that the valve can be raised notonly by the 'expansion ot' suchtube upon the admission ot' steam theretowhen the water in the boiler has -fallen g. to low-water mark, but alsobythe pressure of steam within the boiler; but,so far as we know, theexe pansible tube hasy not been connectedrto the valve in the mannerherein shown; nor has an'air-chamber,

vtor the purpose hereinbefore specified, been used in Witnesses H. M.HOPKINS, HORACE B. DOOLITTLE.

